Thermal compressor

ABSTRACT

A compressor that compresses a working fluid through the direct use of thermal energy. The thermal compressor includes at least two sealed heating containers connected to one another. Compression can take place by periodically isolating and heating the working fluid contained within each heating container to different pressures, such that upon connecting the heating containers, pressure, density, and/or altitude differences between the heating containers induces a flow of the working fluid from one heating container to the other. Thermal energy may be transferred to the working fluid through heat exchangers, electrical heaters/resistors, and/or other devices. The amount of heat provided to each container, as well as the duration of the heating process, may be controlled by a central controlling system.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of and priority to Greece Patent Application No. 20130100487, filed on Aug. 30, 2013, the disclosure of which is herein incorporated by reference as if set forth in its entirety.

TECHNICAL FIELD

In general, various embodiments of this invention relate to the compression of fluid using thermal energy and, specifically, to a compressor having at least two sealed containers arranged in series that are periodically isolated to energize/heat a working fluid contained therein, such that the working fluid is propelled between the containers and through the compressor by natural circulation.

BACKGROUND

Compressors are commonly used mechanical devices, and are widely used for fluid compression and/or fluid circulation in hydraulic networks. Many prior art compressors are rotary compressors that include blades that rotate around a shaft and transfer mechanical energy to a working fluid, thereby increasing a fluid's potential energy. Such blades are typically enclosed in a hull or operate in direct contact with the environment. In addition to rotary compressors, reciprocating compressors are also used in industrial applications, in which the potential energy of a moving piston is utilized in order to compress the working fluid inside a cylinder. In both types of compressors, when the desired compression level is attained, an exhaust valve can open and release the compressed working fluid.

Conventional compressors such as these present a series of disadvantages. One such disadvantage is the inability to utilize thermal energy directly for the compression of a working fluid (i.e., without the prior transformation of the thermal energy to mechanical energy). This limitation precludes the use of such devices in applications where the transformation of the available thermal energy to mechanical energy is not possible, or it can lead to a reduction of an installation's efficiency. Another disadvantage of conventional blade compressors is their high cost and complexity of construction, as they are specifically designed according to the thermodynamic specifications of a particular fluid. Further, conventional compressing devices can exhibit convulsions, or even total stall, during their operation in cases where the compressing fluid enters a two-phase flow zone. Consequently, conventional compressors are not considered suitable to compress a working fluid during a two-phase flow.

Accordingly, there exists a need for an improved compressor that improves upon the disadvantages exhibited by conventional compressors, and particularly a compressor that reduces moving parts and can handle fluids in multiple phases.

SUMMARY OF THE INVENTION

The current invention is related to a compressor that can directly transform thermal energy into potential energy of a working fluid. Moreover, the compressor is compatible with typical installations that would otherwise include a standard compressor, as well as installations where an abundance of thermal energy and a need for compressing a working fluid coexist.

In some embodiments, a compressor includes at least two sealed heating containers of independent size, shape and material, connected in series in which compression takes place successively with the use of thermal energy provided to the working fluid. In some instances, the heating containers are connected by a piping system and are periodically isolated or connected to one another by valves (e.g., solenoid valves). In general, the valves included in the compressor can include any type of appropriate valve which can be controlled using any known method. In some instances, the valves can be controlled by a central controlling system/controller. Through the periodic isolation/connection of the heating containers the working fluid can be propelled from an entering point to an exit point of the thermal compressor through natural circulation. In other embodiments, the heating containers can be compartments of a single pressure vessel, where the compartments to which thermal energy is provided are linked through a system of portable interfaces/diaphragms, thus avoiding the need for a piping system and valves. A portable interface/diaphragm can include a slice of metal, plastic, or other material adapted to move back and forth in order to allow or prevent fluid flow. These systems can be a part of a closed circuit or can operate autonomously between any two points of different pressure in the environment.

In some embodiments, in order to transfer thermal energy to the working fluid, heat exchangers, electrical heaters, or a combination of the two are utilized. Such heat exchangers or electrical heaters can be placed inside or outside of the containers, or can be incorporated in the walls of the containers. In instances in which heat exchangers are used, the heat exchangers can receive thermal energy from a thermal circuit connected to the thermal compressor. The thermal circuit can receive thermal energy from, for example, the waste heat of any installation (e.g., a mechanical installation); the ambient heat of the environment; heat that has been harnessed from geothermal installations; the heat accumulated by solar thermal collectors; a steam generating apparatus; a turbo machine; a photovoltaic cell; an internal combustion engine; a nuclear reactor; a natural gas, diesel, gasoline, coal, biomass, and/or ethanol burner; a natural gas, diesel, gasoline, coal, biomass, and/or ethanol steam generator; excess heat from electrical coils; heat concentrated by mirrors; a concentration power plant (e.g., a solar tower, a linear concentration power plant, a Stirling dish, a linear Fresnel collector, a Parabolic trough); a Stirling engine; a steam engine; a Fracking natural gas fire; thermoelectric materials; heat generated from cooling machines (e.g., air conditioners, refrigerators, etc.); and combinations thereof. The containers can be connected in a way that allows the simultaneous and/or separate heating of the containers through substantially simultaneous and/or separate provision of heat. The amount of heat provided to each container, as well as the duration of the heating process, are conducted in accordance with the timing of the entire system and can be controlled by the central controlling system.

The embodiments of the thermal compressor described herein exhibit several advantages over conventional compressors. First, by compressing the working fluid within the containers using thermal energy (e.g., through the use of heat exchangers), the thermal compressor can directly exploit thermal energy and convert it to potential energy without additional installations (e.g., those required for the transformation of thermal to mechanical energy) that incur significant energy losses, particularly in cases where there is excess exploitable thermal energy. Further, the absence of a fan and moving parts may nullify mechanical losses, as well as the need for scheduled maintenance, thus increasing the efficiency and reliability of the system. Moreover, due to the absence of a fan and associated moving parts, which are usually characterized by complex geometry, the construction of the thermal compressor can be significantly simpler and less expensive than conventional compressors.

In general, in one aspect, embodiments of the invention feature a thermal compressor that includes a first constant volume container having a first heat exchanger adapted to heat a working fluid; a second constant volume container fluidically coupled in series with the first constant volume container, the second constant volume container including a second heat exchanger adapted to heat the working fluid; at least one container connection valve adapted to control flow of the working fluid between the first container and the second container; and a controller, where the first container and the second container are arranged and the controller controls the valve and heating of the working fluid to induce natural circulation from the first container to the second container due to at least one of a difference in pressure, a difference in working fluid density, and a difference in fluid level.

In various embodiments, at least one of the first heat exchanger and the second heat exchanger is adapted to use a thermal fluid, which in some cases can be provided from a closed thermal circuit, to heat the working fluid. The thermal circuit may receive thermal energy from at least one of a thermal solar collector, a turbo machine, a geothermal installation, a steam generating apparatus, a photovoltaic energy saving installation, the ambient heat of the environment, an internal combustion engine, a nuclear reactor, a burner, electrical coils, heat concentrated by mirrors, a concentration power plant, a Stirling engine, a Fracking natural gas fire, thermoelectric materials, and heat generated from cooling machines. In some instances, at least one of the first container and the second container include an electrical resistor, which may be disposed outside the container, insider the container, and/or in a well of the container. In certain instances, the controller is further adapted to isolate operation of the first heat exchanger and the second heat exchanger so that the first heat exchanger and the second heat exchanger heat the working fluid at different times. The controller may be further adapted to control at least one additional valve to selectively isolate the working fluid in at least one of the first container and the second container. In some instances, at least one of the first heat exchanger and the second heat exchanger is adapted to heat the working fluid in an isochoric process to increase pressure of the working fluid contained in at least one of the first container and the second container. The working fluid may be selected from the group consisting of water, atmospheric air, refrigerants (e.g., R134a, R1234yf, R407c, R11, R12, R13, R14, R21, R22, R23, R32, R41, R113, R114, R115, R116, R123, R124, R125, R141b, R142b, R143a, R152a, and combinations thereof), Organic Rankine cycle fluids (e.g., R245fa, R141b, R236fa, R218, R227ea, R236ea, R245ca, R365mfc, RC318, and combinations thereof), ammonia, propane, carbon dioxide, and combinations thereof.

In some instances, the first container is disposed at a first height and the second container is disposed at a second height, where the first height is greater than the second height to induce natural flow from the first heat exchanger to the second heat exchanger. The first heat exchanger may be adapted to heat the working fluid until a first pressure is reached, and the second heat exchanger may be adapted to heat the working fluid until a second pressure is reached. In some cases, the working fluid in the first container and the second container consists of a gas and liquid before heating, and after heating, the working fluid in the first container consists of a gas and liquid and the working fluid in the second container consists of a gas. The thermal compressor may include a second container connection valve, and in some instances liquid may flow from the first container to the second container and gas may flow from the second container to the first container when the container connection valves are opened. In some cases, the first container is adapted to hold the working fluid at a first density and the second container is adapted to hold the working fluid at a second density when the container connection valve is closed to induce natural flow between the first container and the second container when the container connection valve is opened.

The thermal compressor may be adapted to be coupled to a work producing system, which may include an expanding device, a generator, and a work system heat exchanger, where the working fluid travels through the work producing system. In some instances, the work producing system is configured to provide, through natural circulation, a mass transfer of the working fluid from the work producing system to the first container after the working fluid exits the work system heat exchanger. In such instances, the work producing system may further include at least one buffer tank disposed between the first container and the work system heat exchanger. In some instances, the work producing system is configured to provide, through natural circulation, a mass transfer of the working fluid from the second container to the work producing system before the working fluid enters the expanding device. In such instances, the work producing system may further include at least one buffer tank disposed between the second container and the expanding device. In some instances, the container connector valve includes a portable interface to selectively obstruct flow. In certain embodiments, the thermal compressor can include at least one additional container arranged in series with the first container and the second container. In some cases, the thermal compressor is adapted to be coupled to a heat pump, which can include a compressor, a condenser, an expansion element, and an evaporator.

In general, in another aspect, embodiments of the invention feature a method of thermally compressing a working fluid. The method may include the steps of heating a working fluid in a first constant volume container with a first heat exchanger, heating the working fluid in a second constant volume container with a second heat exchanger, and controlling at least one container connection valve disposed between the first container and the second container to allow natural circulation of the working fluid from the first container to the second container based on at least one of a difference in pressure, a difference in working fluid density, and a difference in fluid level.

In various embodiments, the working fluid may be heated in an isochoric process. In some instances, the first heat exchanger heats the working fluid when pressure in the first container is below a threshold value. In such instances, the second container may transfer the working fluid to a working circuit during heating of the working fluid by the first heat exchanger, and a thermal circuit may circulate a thermal fluid through the first heat exchanger to heat the working fluid. In other instances, the second heat exchanger heats the working fluid when pressure in the second container is below a threshold value. In such instances, the first container may receive the working fluid from a working circuit during heating of the working fluid by the second heat exchanger, and a thermal circuit may circulate thermal fluid through the second heat exchanger to heat the working fluid. In some cases, the second heat exchanger heats the working fluid before the first heat exchanger heats the working fluid within a cycle. The valve may be opened after the first heat exchanger and the second heat exchanger have heated the working liquid. In certain embodiments, a density in the first container is greater than a density in the second container to promote natural circulation.

BRIEF DESCRIPTION OF THE FIGURES

In the drawings, like reference characters generally refer to the same parts throughout the different views. Also, the drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention. In the following description, various embodiments of the present invention are described with reference to the following drawings.

FIG. 1 is a schematic fluid circuit diagram of a thermal compressor connected to a thermal circuit and a work producing system that generates electricity, according to one embodiment.

FIGS. 2A, 2B are a schematic semi-transparent side view and non-transparent perspective view, respectively, of a container including an electrical resistor within its interior according to one embodiment.

FIGS. 3A, 3B are a schematic semi-transparent side view and non-transparent side view, respectively, of a container having an electrical resistor wreathed about its exterior, according to one embodiment.

FIG. 4 is a schematic, semi-transparent side view of an exemplary configuration of the thermal compressor during heating of working fluid in a container, according to one embodiment.

FIG. 5 is a schematic, semi-transparent side view of an exemplary configuration of the thermal compressor during mass transfer of working fluid into and out of the thermal compressor, according to one embodiment.

FIG. 6 is a schematic, semi-transparent side view of an exemplary configuration of the thermal compressor during heating of working fluid in another container, according to one embodiment.

FIG. 7 is a schematic, semi-transparent side view of an exemplary configuration of the thermal compressor during mass transfer of working fluid between two containers through natural circulation, according to one embodiment.

FIG. 8 is a table showing the states of the working fluid contained within the containers at various phases of a thermal compression cycle, according to one embodiment.

FIGS. 9A-9C are tables with exemplary operating parameters for a turbine in a work producing system for use with the thermal compressor system shown in FIG. 1, according to one embodiment.

FIG. 10 is a schematic, fluid circuit diagram of a thermal compressor, according to one embodiment.

FIG. 11 is a schematic, fluid circuit diagram of a thermal compressor, according to another embodiment.

FIG. 12 is a schematic, fluid circuit diagram of a thermal compressor having three containers, according to one embodiment.

FIG. 13 is a schematic, fluid circuit diagram of two thermal compressors in parallel connected to a thermal circuit, according to one embodiment.

DETAILED DESCRIPTION

Embodiments of the present invention are directed to a compressor that compresses a working fluid with direct use of thermal energy (e.g., from the environment or as the waste from an installation, amongst other heat sources). In general, the compressor of the present invention can be used in conjunction with any working fluid, for example, water, atmospheric air, refrigerants (e.g., R134a, R1234yf, R407c, R11, R12, R13, R21, R22, R23, R32, R41, R113, R114, R115, R116, R123, R124, R125, R141b, R142b, R143a, R152a), Organic Rankine cycle fluids (e.g., R245fa, R141b, R236fa, R218, R227ea, R236ea, R245ca, R365mfc, RC318), ammonia, propane, carbon dioxide, and combinations thereof. Certain embodiments of the compressor are described in greater detail below in conjunction with the accompanying drawings.

In a first embodiment, depicted in FIG. 1, a thermal work system 137 includes a thermal compressor 16 connected to a thermal circuit 135 that provides heat to the thermal compressor 16 and a work producing system 136. FIG. 1 depicts an embodiment of the thermal circuit 135 with a thermal energy input 1 (e.g., a solar thermal collector). A solar thermal collector can be used to exploit the excess heat accumulated on such collectors by converting the solar thermal collector 1 into a cogeneration unit that produces electricity in addition to hot water. The electricity generated can be directly utilized for domestic consumption, and can therefore reduce a household's electricity consumption from the grid. The thermal energy input 1 can receive thermal energy from any known thermal energy source (e.g., the waste heat of any installation, the ambient heat of the environment, heat that has been harnessed from geothermal installations, etc.). Further, while FIG. 1 depicts use of compressed fluid from the thermal compressor 16 with the work producing system 136 to generate electricity, in general, the thermal compressor 16 can be used in conjunction with any system that uses compressed fluid. For example, the thermal compressor 16 can be used in conjunction with a heat pump.

In various embodiments, the thermal compressor 16 includes a first container 5 and a second container 6. The containers 5, 6 may each have a constant volume. In some embodiments, the first container 5 may have a smaller volume than the second container 6. Fluid (e.g., a working fluid) within the containers 5, 6 can be heated using heating elements 133, 134, that include, for example, heat exchangers, electrical heaters, electrical resistors, or combinations thereof. In embodiments in which electrical resistors are used, in some instances the electrical resistors can be located within the interior of the heat containers 5, 6, as depicted, for example, in FIGS. 2A and 2B. In other instances, the electrical resistors can be wreathed around the exterior of the heat containers 5, 6, as depicted for example in FIGS. 3A and 3B. The containers 5, 6 may include pressure sensors 206, 208, respectively, to sense pressure of the working fluid therein. The containers 5, 6 may include pressure safety valves 205, 207, respectively, to protect the containers 5, 6 from excessive pressures. In some embodiments, the container 5 is connected to the container 6 by a pipe 132 including a container connection valve 109 (e.g., a solenoid valve). In other embodiments, as shown for example in FIGS. 4-7, the containers 5, 6 are connected using a double pipe and valve system having, for example, an upper pipe 132 a including an upper container connection valve 109 a and a lower pipe 132 b including a lower container connection valve 109 b. In other embodiments, the containers 5, 6 may be compartments of a single pressure vessel and connected through a system of portable interfaces/diaphragms. The connection(s) between the containers 5, 6 can also be controlled by poppet valves, moving interfaces, or any other device capable of controlling flow through a pipe (or pipes) placed between the containers 5, 6. The container 5 can receive working fluid requiring compression from the work producing system 136, such as working fluid exiting an expanding device 10 (described in greater detail below). The flow of working fluid into the container 5 can be controlled by a valve 115. The container 6 can deliver a compressed working fluid to the work producing system 136. The flow of compressed working fluid can be controlled by a valve 110. The operation of any valves in the thermal circuit 135, the thermal compressor 16, and the work producing system 136, or a subset thereof, can be controlled by a central controlling system (or controller) 116, for example, in response to measurements observed by various pressure and temperature sensors throughout the thermal work system 137 to achieve a desired thermodynamic state within the thermal work system 137.

In various embodiments, the containers 5, 6 can be isolated from each other (e.g., by closing the valve 109), allowing a different amount of thermal energy to be provided to the container 5 than is provided to the container 6. By enabling isolation of the containers 5, 6 from each other, the pressure and/or density of the working fluid contained within the container 5 can be controlled to be greater than the pressure and/or density of the working fluid contained within the container 6 at select times during the cycle. Further, in some embodiments, the container 5 can be installed at a higher altitude (“level”) than the container 6. Following the isolation and separate provision of thermal energy to the containers 5, 6, the containers 5, 6 can be connected to one another (e.g., using either a single pipe or a double pipe arrangement), at which point the pressure, density, and/or level difference between the containers induces flow of the working fluid from the container 5 to the container 6. This flow of fluid created by such pressure, density, and/or level differences (and characterized by generally few or a total absence of moving mechanical parts driving the working fluid) is referred to as “natural circulation.” A description of one embodiment of the system 137 operating according to these principles is described below in reference to FIG. 1.

As shown in the embodiment depicted in FIG. 1, the thermal compressor 16 is connected to the work producing system 136. In the embodiment shown, the work producing system 136 includes a buffer tank 7, which can contain or be wreathed in an electrical resistor 8 to which voltage is provided by, for example, a battery 9 or a portion of the electricity generated by the work producing system 136. The buffer tank 7 may be equipped with a pressure transmitter 209, a thermometer (or temperature sensor) 211, and a pressure safety valve 210. A valve 111 and a flow regulating valve 212 can be placed between the buffer tank 7 and the turbine 10. The turbine 10 (or other expansion device) can be connected to an electrical generator 11, which converts the mechanical energy of the turbine 10 into electricity. In some embodiments, the electrical generator 11 and the turbine 10 are equipped with electronic sensors 213 and/or controllers 214, which provide information regarding the status of their operation. The working fluid exiting the turbine 10 may enter a condenser (or work system heat exchanger) 12 (in some instances via a valve 112). The condenser 12 can have a pressure meter 215 and/or a thermometer 216 installed at its outlet in order to, for example, monitor and/or regulate the operation of the work producing system 136. Following the condenser 12, the working fluid may flow through a check valve 113 and a valve 114 before entering a buffer/suction tank 13. The buffer tank 13 can potentially contain or be wreathed in an electrical resistor 14, to which voltage is provided by, for example, a battery 15 or a portion of the electricity generated by the work producing system 136. The buffer tank 15 may be equipped with a pressure transmitter 218 and a pressure safety valve 217. In some embodiments, the inlet of the thermal compressor 16 is connected to the buffer tank 13 via the valve 115. In embodiments in which the thermal compressor 16 is coupled to a heat pump, the heat pump can include a similar system as the work producing system 136 described above, but with an evaporator 140 and fluid flowing in the opposite direction.

As shown in FIG. 1, the thermal compressor 16 may receive thermal energy from the thermal circuit 135 that includes a thermal energy input (e.g., a solar thermal collector) 1 that collects, delivers, and/or heats a thermal fluid (e.g., water/antifreeze solution) using solar energy. Although this disclosure refers to solar heated water/antifreeze solution, other thermal fluids can be used as well, such as water, atmospheric air, refrigerants (e.g., R134a, R1234yf, R407c, R11, R12, R13, R21, R22, R23, R32, R41, R113, R114, R115, R116, R123, R124, R125, R141b, R142b, R143a, R152a), Organic Rankine cycle fluids (e.g., R245fa, R141b, R236fa, R218, R227ea, R236ea, R245ca, R365mfc, RC318), ammonia, propane, carbon dioxide, and combinations thereof. In some instances, the thermal circuit 135 delivers heated thermal fluid from the thermal solar collector 1 to a storage/heater tank 3, in some cases transporting the thermal fluid through the valves 102 and 104 to a heat exchanger contained in the storage/heater tank 3, in order for the fluid in the storage/heater tank 3 to be heated for domestic or other use. Heated thermal fluid can also be transported from the heat exchanger contained in the storage/heater tank 3 to an expansion tank 4, in some cases through a valve 105. In addition to the expansion tank 4, the thermal circuit 135 can also include a pressure safety valve 203 to protect the system 137 from potentially destructive pressure levels. In other instances, the thermal circuit 135 delivers heated thermal fluid from solar thermal collector 1 to a heat exchanger 133 for heating working fluid in the container 5, and to heat exchanger 134 for heating working fluid in the container 6 of the thermal compressor 16. In some cases, the heated thermal fluid can be delivered to the thermal compressor 16 by transporting it through a valve 101, a circulator 2, and a check valve 103.

In various embodiments, when the temperature of the thermal fluid in the storage/heater tank 3 (which can be monitored by a temperature sensor 202) surpasses a predetermined value, and/or the temperature of the thermal fluid flowing through the thermal circuit 135 (which can be monitored by a thermometer 201) surpasses a predetermined value, circulation of working fluid in the work producing system 136 is initiated, allowing for expansion of compressed working fluid to produce electricity.

In some embodiments, measurements from the pressure sensors 206, 208, 209, 215, 218 and the thermometers 211, 216 are gathered. Based on these measurements, working fluid in the buffer tanks 7, 13 can be isochorically heated (i.e., such that temperature and pressure are increased at a constant volume) using the electrical resistors 8, 14, or another heat source, until the pressure and/or density of the working fluid reaches a desired level. The valves 110, 111, 112, 114, 115 may be controlled by the controller 116 to induce an initial flow of working fluid in the work producing system 136. Once the desired thermodynamic state of the work producing system 136 is attained (e.g., natural circulation is induced across the turbine 10, to the container 5, and/or from the container 6) the heating of working fluid in the buffer tanks 7, 13 may cease. However, such heating may continue and/or resume if, for example, the thermodynamic state of the work producing system 136 deviates from its desired state. As long as the turbine 10 and the electrical generator 11 do not emit a malfunction signal, the valve 111 may remain open in order to allow the transfer of working fluid from the buffer tank 7 to the turbine 10. A flow adjustment valve 212 may adjust the amount of working fluid provided to the turbine 10 in order for the electrical generator 11 to operate at the desired operating point. The working fluid exiting the turbine 10 (e.g., in the form of superheated steam) may enter the condenser 12, and after being condensed into a liquid, be transported to and accumulated in the buffer tank 13. In some embodiments, the check valve 113 ensures that the flow of the working fluid is directed towards the buffer tank 13 and not permitted to backflow.

In parallel with the above-described operation of the work producing circuit 136, the thermal circuit 135 can also be in operation. In some embodiments, as soon as the pressure in the container 6 is lower than a predetermined level, the valve 107 may be opened, the valve 104 may be closed, and a valve 106 a may be opened (while a valve 106 b is closed) to direct heated thermal fluid in the thermal circuit 135 to a heat exchanger 134 coupled to (e.g., contained within) the container 6. In some embodiments, when closing the valve 102 and opening the valve 101, a circulator 2 is set into motion at a volumetric flow rate such that an appropriate amount of heat is transferred to the working fluid contained within the container 6, thereby isochorically heating the working fluid to a desired pressure and density. Heating the working fluid in the container 6 to such desired pressure may result in the fluid being heated from a liquid (or liquid/gas mixture) into a gas without any liquid. The volumetric flow rate of the thermal fluid and transfer of thermal energy to the working fluid can be based on a variety of measurements in the thermal circuit 135, including those taken by the thermometers 201, 204. The check valve 103 can be placed in a depression of the circulator 2 so as to prevent the working fluid from flowing backwards towards the circulator 2.

At the same time as working fluid in the container 6 is being heated, the valve 115 may be open in order to allow the transfer of working fluid from the buffer tank 13 to the container 5. The working fluid transitions from Phase 3 to Phase 1, as indicated in FIG. 8 and described below. Such fluid transfer may occur by natural circulation and be induced by a pressure, density, and/or level difference between the working fluid contained within the buffer tank 13 and the container 5. As the working fluid being transferred from the buffer tank 13 to the container 5 has already passed through the condenser 12, it may be in a liquid phase. FIG. 4 shows an example configuration of the thermal compressor 16 during this process in an embodiment in which the containers 5, 6 are connected by a double piping system with the pipes 132 a, 132 b and the valves 109 a, 109 b. In this embodiment, the valves 109 a, 109 b, 110 are closed in order to isolate working fluid within the container 6 as the working fluid is heated to a gas. In some embodiments, as shown for example in FIG. 5, if the working fluid contained in the container 6 reaches its desired pressure and/or density before the mass transfer between the buffer tank 13 and the container 5 is complete, the valve 110 may open and the working fluid in a gas phase in the container 6 may flow to the buffer tank 7 while the working fluid in the liquid phase is still entering the container 5. The working fluid may flow naturally from the container 6 to the buffer tank 7 due to higher pressure in the container 6 than the buffer tank 7.

Once the pressure of the working fluid within the container 6 reaches a desirable level, the valve 107 can be closed to cease heating the working fluid in the container 6. At the same time, the container 5 may be isolated and heating of the working fluid contained therein may begin. This process transitions the working fluid from Phase 1 to Phase 2, as described in FIG. 8 (described below). For example, the valves 106 b, 108 may be opened and the valve 106 a closed to direct the thermal fluid a heat exchanger 133 coupled to (e.g., contained within) the container 5. FIG. 6 shows an example configuration of the thermal compressor 16 during this process. In this embodiment, the valves 109 a, 109 b, and 115 are closed while the working fluid (e.g., in liquid or liquid/gas form) contained in the container 5 is heated. The amount of thermal energy delivered to the container 5 may be controlled by adjusting the volumetric flow rate of the circulator 2 (which can take into account the temperature readings of the thermometers 201, 204) such that the working fluid contained within the container 5 is isochorically heated to a desired state (e.g., a greater pressure and/or greater density than the working fluid in the container 6). Heating the working fluid in the container 5 to such desired pressure may result in the working fluid transitioning from a liquid into a liquid/gas mixture. As shown in FIG. 6, while the working fluid within the container 5 is being heated, the valve 110 may be open in order to allow mass transfer of working fluid from the container 6 to the buffer tank 7. Such working fluid mass transfer may occur by natural circulation, as can be induced by a pressure, density, and/or level difference between the working fluid contained within the container 6 and the working fluid in the buffer tank 7. Once a desired amount of working fluid has been transferred from the container 6 to the buffer tank 7, the valve 110 may be closed to isolate the container 6 from the buffer tank 7.

When the pressure and density of the working fluid within the container 5 reaches a desired level, the valves 101, 106 b, 108 may close, isolating the containers 5, 6 from the thermal circuit 135. In some embodiments, when the containers 5, 6 are isolated, the valves 102, 104, 105 are opened and heated thermal fluid exiting the solar thermal collector 1 is directed into the heat exchanger contained in the storage/heater tank 3. In addition, the valves 110, 115 may be closed and the containers 5, 6 may be isolated from the work producing system 136, as well. Following the isolation of the containers 5, 6 from the thermal circuit 135 and the work producing system 136, the containers 5, 6 can be fluidically connected to each other to allow for the flow of working fluid from the container 5 to the container 6 by natural circulation (i.e., induced by a pressure, density, and/or level difference between working fluid in the containers 5, 6). This process causes the working fluid to transition from Phase 2 to Phase 3, as identified in FIG. 8. In an embodiment in which the container 5 is connected to the container 6 by a single pipe 132, such connection can occur by opening the valve 109. In an embodiment in which the container 5 is connected to the container 6 by a double pipe system, as depicted in FIG. 7, such connection can occur by opening the valves 109 a, 109 b, leading to natural circulation of working fluid between the containers 5, 6. In such an embodiment, after heating of working fluid in the container 5 when the container 5 contains a liquid/gas mixture and the container 6 contains a gas (Phase 2 in FIG. 8), movement of working fluid between the containers 5, 6 can occur with few or no mechanical parts driving the flow of working fluid. Liquid of the liquid/gas mixture is located in the lower portion of the container 5 and the gas is located in the upper portion of the container 5 based on differences in density. In this embodiment, the density of the working fluid contained in the container 5 may be greater than the density of the working fluid contained in the container 6 (e.g., the density of the liquid/gas mixture in the container 5 is greater than the density of the gas in the container 6). The density differences can induce flow of the liquid working fluid from the container 5 through the pipe 132 b (which connects the lower portion of the container 5 to the lower portion of the container 6) into the container 6. Because the container 6 is of fixed volume and the valve 110 is closed, the flow of liquid into the container 6 may force some of the working fluid in gaseous form from the container 6 to the container 5 through the pipe 132 a (which connects an upper portion of heating container 6 to an upper portion of heating container 5). The induced flow between the containers 5, 6 can continue until the pressure within the two heating containers becomes equal (e.g., until the pressure sensors 206, 208 emit the same signal), which in some cases can take several seconds, at which time the valve 109 (or the valves 109 a, 109 b) may be closed.

At this point, the disclosure has described an exemplary complete cycle of the operation of the thermal compressor 16 of the present invention when used in conjunction with the thermal circuit 135 and the work producing system 136, as shown in FIG. 1. Subsequently, the cycle may be repeated, starting with the isolation and heating of working fluid contained within the container 6, and transitioning the working fluid from Phase 3 to Phase 1, as identified in FIG. 8.

In some embodiments, in a situation in which any sensor or central controlling system 116 emits a malfunction and/or error signal, the system 137 described above may cease its function. In such situations, once functionality is restored, the entire process described above, starting with generating an initial flow in the work producing system 136 (e.g., by isochorically heating working fluid in the buffer tanks 7, 13), can be repeated.

The work producing system 136 can operate effectively when paired with the thermal compressor 16. FIGS. 9A-9C include exemplary operating parameters for the system 136 at the turbine 10.

As described above, the thermal compressor 16 can receive thermal energy from a wide variety of thermal energy sources, including from the waste heat of any installation (e.g., a mechanical installation); the ambient heat of the environment; heat that has been harnessed from geothermal installations; the heat accumulated by solar thermal collectors; a steam generating apparatus; a turbo machine; a photovoltaic cell; an internal combustion engine; a nuclear reactor; a natural gas, diesel, gasoline, coal, biomass, and/or ethanol burner; a natural gas, diesel, gasoline, coal, biomass, and/or ethanol steam generator; excess heat from electrical coils; heat concentrated by mirrors; a concentration power plant (e.g., a solar tower, a linear concentration power plant, a Stirling dish, a linear Fresnel collector, a Parabolic trough); a Stirling engine; a steam engine; a Fracking natural gas fire; thermoelectric materials; and heat generated from cooling machines (e.g., air conditioners, refrigerators, etc.). Further, the working fluid compressed by the thermal compressor 16 can be used in a wide variety of applications, including the compression of air and/or other fluids, solar and/or conventional cooling applications, desalination applications, refrigeration, Stirling engine applications, thermoelectric applications, internal combustion engine applications, turbo machinery applications, large scale steam turbine applications, power production applications, automobile driving power applications, and combinations thereof. This flexibility is an asset, and FIGS. 10, 11, and 12 depict examples of thermal compressors 16 in isolation that can be installed in many installations requiring a compressor, including those that also have a source of thermal energy.

In various embodiments, the valves 106 a, 106 b (e.g., solenoid valves) may be replaced by a single three-way valve 106, as shown, for example, in FIG. 10. In such embodiments, in situations in which heated thermal fluid is delivered to the container 6, the valve 106 can direct thermal fluid to the container 6 while precluding flow to the container 5. The opposite applies when thermal fluid is to be delivered to the container 5.

In various embodiments, the thermal compressor 16 can include three (or more) heating containers 5, 6, 20, as shown, for example, in FIG. 12. Although FIG. 12 shows a system including three heating containers, the same principles can be applied to add as many heating containers to the thermal compressor 16 as desired. In some instances, the pressure, density, and/or level difference(s) between the container 5 and the container 6 may not generate desirable thermodynamic and/or flow conditions. To improve performance, one option is to add the third heating container 20 to the thermal compressor 16. Similar to the containers 5, 6, the container 20 may include a pressure sensor 220 and a pressure safety valve 221. The addition of more heating containers can allow the working fluid to reach its desired state in more than two stages. The container 20 can be isolated and separately heated in the same manner as described above regarding the isolation and separate heating of the container 5 and the container 6. The container 20 can be separately heated by, for example, closing the valves 107, 108, opening the valve 130, and having the four-way valve 106 direct heated thermal fluid from the thermal circuit 135 to a heat exchanger 138 coupled to the container 20. The container 20 can be isolated from the work producing system 136 and other containers 5, 6 by, for example, closing a valve 131 (or analogous valves in a double pipe connection embodiment) and the valve 110. The working fluid contained within the container 20 can be heated to a pressure and/or a density, and/or kept at an elevation, that induces the flow of working fluid from the container 6 to the container 20 by natural circulation. The working fluid can be induced to flow from the container 5 to the container 6 in the same manner as described above with respect to FIG. 1. The addition of additional heating containers can result in less energy being required to achieve a desired pressure increase.

In various embodiments, the thermal compressors described above may be used in parallel (e.g., thermal compressors 16 a, 16 b in FIG. 13) to improve temporal continuity and attain a substantially constant volumetric flow rate at an outlet 139 of the thermal compressors 16 a, 16 b. Such operation can be useful in situations where the outlet 139 of the thermal compressors 16 a, 16 b is connected to a device that requires constant fluid flow to operate (e.g., certain turbines or other expanders). As depicted in FIG. 13, the first thermal compressor 16 a includes a container 5 a and a container 6 a, which is arranged in parallel to a second thermal compressor 16 b including a container 5 b and a container 6 b. Although FIG. 13 only shows two thermal compressors 16 a, 16 b in parallel, in other embodiments, more thermal compressors can be included.

Each numerical value presented herein, for example, in a table or a chart, is contemplated to represent an exemplary value in a range for a corresponding parameter. Accordingly, when added to the claims, the numerical value provides express support for claiming a range around that value, which may lie above or below the numerical value, in accordance with the teachings herein. Absent inclusion in the claims, each numerical value presented herein is not to be considered limiting in any regard.

The terms and expressions employed herein are used as terms and expressions of description and not of limitation, and there is no intention, in the use of such terms and expressions, of excluding any equivalents of the features shown and described or portions thereof. In addition, having described certain embodiments of the invention, it will be apparent to those of ordinary skill in the art that other embodiments incorporating the concepts disclosed herein may be used without departing from the spirit and scope of the invention. The structural features and operational functions of the various embodiments may be arranged in various combinations and permutations, and all are considered to be within the scope of the disclosed invention. Accordingly, the described embodiments are to be considered in all respects as only illustrative and not restrictive. Furthermore, the configurations, materials, and dimensions described herein are intended as illustrative and in no way limiting. Similarly, although physical explanations have been provided for explanatory purposes, there is no intent to be bound by any particular theory or mechanism, or to limit the claims in accordance therewith. 

1. A thermal compressor comprising: a first constant volume container comprising a first heat exchanger adapted to heat a working fluid; a second constant volume container fluidically coupled in series with the first constant volume container, the second constant volume container comprising a second heat exchanger adapted to heat the working fluid; at least one container connection valve adapted to control flow of the working fluid between the first container and the second container; and a controller, wherein the first container and the second container are arranged and the controller controls the valve and heating of the working fluid to induce natural circulation from the first container to the second container due to at least one of a difference in pressure, a difference in working fluid density, and a difference in fluid level.
 2. The thermal compressor of claim 1, wherein at least one of the first heat exchanger and the second heat exchanger is adapted to use a thermal fluid to heat the working fluid.
 3. The thermal compressor of claim 2, wherein the thermal fluid is provided from a closed thermal circuit.
 4. The thermal compressor of claim 3, wherein the thermal circuit receives thermal energy from at least one of a thermal solar collector, a turbo machine, a geothermal installation, a steam generating apparatus, a photovoltaic energy saving installation, the ambient heat of the environment, an internal combustion engine, a nuclear reactor, a burner, electrical coils, heat concentrated by mirrors, a concentration power plant, a Stirling engine, a Fracking natural gas fire, thermoelectric materials, and heat generated from cooling machines.
 5. The thermal compressor of claim 1, wherein at least one of the first container and the second container comprise an electrical resistor.
 6. The thermal compressor of claim 5, wherein the electrical resistor is disposed at least one of outside the container, inside the container, and in a well of the container.
 7. The thermal compressor of claim 1, wherein the controller is further adapted to isolate operation of the first heat exchanger and the second heat exchanger so that the first heat exchanger and the second heat exchanger heat the working fluid at different times.
 8. The thermal compressor of claim 1, wherein the controller is further adapted to control at least one additional valve to selectively isolate the working fluid in at least one of the first container and the second container.
 9. The thermal compressor of claim 1, wherein at least one of the first heat exchanger and the second heat exchanger is adapted to heat the working fluid in an isochoric process to increase pressure of the working fluid contained in at least one of the first container and the second container.
 10. The thermal compressor of claim 1, wherein the working fluid is selected from the group consisting of water, atmospheric air, refrigerants, Organic Rankine cycle fluids, ammonia, propane, carbon dioxide, and combinations thereof.
 11. The thermal compressor of claim 10, wherein the refrigerant is selected from the group consisting of R134a, R1234yf, R407c, R11, R12, R13, R14, R21, R22, R23, R32, R41, R113, R114, R115, R116, R123, R124, R125, R141b, R142b, R143a, R152a, and combinations thereof.
 12. The thermal compressor of claim 11, wherein the Organic Rankine cycle fluid is selected from the group consisting of R245fa, R141b, R236fa, R218, R227ea, R236ea, R245ca, R365mfc, RC318, and combinations thereof.
 13. The thermal compressor of claim 1, wherein the first container is disposed at a first height and the second container is disposed at a second height, and wherein the first height is greater than the second height to induce natural flow from the first heat exchanger to the second heat exchanger.
 14. The thermal compressor of claim 1, wherein the first heat exchanger is adapted to heat the working fluid until a first pressure is reached and the second heat exchanger is adapted to heat the working fluid until a second pressure is reached.
 15. The thermal compressor of claim 14, wherein the working fluid in the first container and the second container consists of gas and liquid before heating.
 16. The thermal compressor of claim 14, wherein the working fluid in the first container consists of gas and liquid and the working fluid in the second container consists of gas after heating.
 17. The thermal compressor of claim 16 further comprising a second container connection valve.
 18. The thermal compressor of claim 17, wherein liquid flows from the first container to the second container and gas flows from the second container to the first container when the container connection valves are opened.
 19. The thermal compressor of claim 1, wherein the first container is adapted to hold the working fluid at a first density and the second container is adapted to hold the working fluid at a second density when the container connection valve is closed to induce natural flow between the first container and the second container when the container connection valve is opened. 20.-29. (canceled)
 30. A method of thermally compressing a working fluid, the method comprising the steps of: heating a working fluid in a first constant volume container with a first heat exchanger; heating the working fluid in a second constant volume container with a second heat exchanger; and controlling at least one container connection valve disposed between the first container and the second container to allow natural circulation of the working fluid from the first container to the second container based on at least one of a difference in pressure, a difference in working fluid density, and a difference in fluid level. 31.-40. (canceled) 